For supporting 3D, e.g., stereoscopic, image capture, pairs of cameras are sometimes used. Fisheye camera lenses are sometimes used for cameras of stereoscopic pairs. It can be important to compensate for distortions introduced by individual fish eye lenses if a high image quality is desired.
Camera lenses of individual cameras may be calibrated based on a particular orientation in the camera in which the lens is used. If the lens orientation changes, e.g. a lens is rotated unintentionally from the position at which it was calibrated, correction information for the lens generated during calibration may no longer be applicable since it is intended to be used with a particular lens orientation and may in fact degrade image quality if used rather than enhance it. In addition to lens orientation and/or alignment, correct spacing between camera lenses of a stereoscopic camera pair can be important for quality stereoscopic images captured using camera pairs, e.g., left and right eye cameras.
While lenses, cameras and/or camera pairs used for stereoscopic image capture may be calibrated and aligned prior to shipment, during shipment the cameras and/or camera pairs are often subject to shocks which can alter the careful alignment of the cameras and/or lenses. Unfortunately at a sports stadium or other site where the cameras may be used to capture images, the camera operator or field technician may not have a large calibration apparatus available to check the alignment and spacing of cameras of a stereoscopic camera pair and/or the components of such a camera pair. As should be appreciated miss-alignment of camera components and/or miss-spacing of cameras of a stereoscopic camera pair can significantly impact the quality of captured stereoscopic image content.
A significant problem with attempting to use camera pairs to capture images that have been subject to the stress and shocks of shipment to a site where they are to be used and/or subject to stress or shocks that may be incurred during normal use at a site, is that the cameras of a camera pair, or the components of a camera pair may become miss-aligned or miss-spaced relative to one another. For example, one camera lens may be angled slightly differently than the lens of the other camera, rotated relative to its original calibration position and/or the spacing between camera lenses may be different from what is intended.
In view of the above it should be appreciated that there is a need for methods and apparatus which allow a field technician to check camera alignment, camera spacing and/or alignment of the components of a stereoscopic pair and/or which would allow a field technician to perform a calibration of a camera pair in the field, e.g., at the site where the camera pair is to be used.
While not necessary for all embodiments it would be desirable if in at least some embodiments the tools and/or devices used as part of performing a field calibration were easy to transport and/or use at a site where a stereoscopic camera pair is to be used to capture images.
In view of the above it should be appreciated that there is a need for methods and/or apparatus that can be used to facilitate achieving a desired alignment of one or more camera pairs and/or components and/or which can be used to facilitate a field calibration of cameras or camera components of a stereoscopic camera pair.